Page "Von Neumann entropy" Paragraph 67

Conversely, quantum measurement cannot be claimed to reveal the properties of a system that existed before the measurement was made.

This controversy has encouraged some authors to introduce the non-additivity property of Tsallis entropy ( a generalization of the standard Boltzmann – Gibbs entropy ) as the main reason for recovering a true quantal information measure in the quantum context, claiming that non-local correlations ought to be described because of the particularity of Tsallis entropy.